Thermostat



Aug. 6, 1940. E. BLETZ 2,210,701

- THERMOSTAT Filed April 25, 1939 WITNESSES: INVENTOR @Zw 77/1 QW/W fdM/ara 57652.

'ATTORNEY- L/ Patented Aug. 6, 1940 UNITED STATES PATENT OFFICE THERMOSTAT vania Application April 25, i939, Serial No. 269,939

7 Claims.

My invention relates to thermostats, and more particularly to bimetallic snap-acting strip-type thermostats.

An object of :myy invention is to provide an efcient, inexpensive, rugged, snap-acting, bimetallic, strip-type thermostat which may be operated by an ambient temperature or by an electric current passing therethrough.

A further object of my invention is to provide a.

thermostat having a furcated bimetallic member in which at least one leg of the member is in compression and one leg is in tension` Y Another object of my invention is to provide a thermostat having a furcated bimetallic member in which one leg is in compression, and adjusting means which cooperates with. the supporting structure and the compressed iurcation.

Still another object of my invention is to provide a bimetallic thermostat having a furcated bimetallic member in which lone of the furcations thereof is under compression and having a resetting mechanism resiliently mounted upon the supporting structure and cooperating with the bimetallic member for resetting such member upon its automatic disengagement.

Other objects of my invention will either be pointed out specifically in the course of the following description of a device embodying my invention, or will be apparent from such descrip- ..0 tion.

In the accompanying drawing:

Figure 1 is a plan view of the bimetallic element incorporated in a device embodying my invention;

3 Fig. 2 is a plan view of the supporting structure for the device embodying my invention;

Figs. 3 and 4 are side elevational views of the device embodying my invention illustrating its operative and inoperative positions;

Fig. 5 is a diagrammatic view illustrating a modified form of an adjusting mechanism for the device shown in Figs. 3 and 4;

Figs. 6 and 7 are plan and side views, respectively, of a modiied form of a bimetallic member adapted to be used in the device illustrated in Figs. 3 and 4;

Figs. 8 and 9 show a plan and side elevational view of a second modified form of bimetallic member of a device embodying my invention, and

Figs. 10 and 11 show diagrammatic views of a device embodying my invention incorporated with a power circuit. 4

Referring to the accompanying drawing, I show a thermostat I0 having a base or supporting structure I2, a furcated bimetallic member I4, co-

(Cl. 20D-138) operating contacts I6 and I8, adjusting means 28 cooperating with the supporting structure and the bimetallic member, adjusting means 22 cooperating with the supporting structure I2 and the free end of the bimetallic member I4, and 5 a manual reset mechanism 24 for manually resetting the thermostat.

The base I2 comprises, in this instance, a substantially iiat strip of metal through which there extends a plurality of apertures 28, 30, 32, 34, 35 10 and 36 for purposes hereinafter described. It is to be understood, however, that the base I2 may .be formed from any other suitable material such as a phenolic resin. A right-angle-shaped supporting ledge 26 is rigidly-attached to one end of l5 the base I2, its legs being respectively located in line with the apertures 34, and 36. Further, the apertures 34, 35 and 36 extend through the supporting ledge 26. The apertures 35 and 36 are substantially on a line parallel to the transverse 20 axis of the supporting structure I2.

The bimetallic member I4 is, in this instance, bifurcated, having furcations or prongs 38 and 40 and an end portion 42. The end portion 42 1s, in this instance, integral with the iurcations 38 25 and 49. However, it is to be understood that such end portion may be a separate integral member rigidly attached to the furcations 38 and 43 to form a functionally integral furcated bimetallic member. Furcations 38 and 40 are, in 30 the preferred form, substantially the same length and have apertures 39, 4I and 43 located in the end thereof. Apertures 33 and il are in the end of the furcation 38, while the aperture 43 is positioned within the end of the furcation 40. It 35 will be noted that the apertures 4I and 43 are not along a transverse axis of the overall birnetallic member i4. In other words, the apertures 4I and 43 are substantially oiset, with respect to each other, and are adapted to cooperate with the apertures 35 and 36 of the supporting structure l2 infa manner as hereinafter described. An aperture 44 is located in the end portion 42 of the bimetallic member I4 for the purpose of retaining the movable contact I8. Such contact I8 45 is attached to the end portion 42 by means of suitable nuts and bolts, or the like, 46.

Stationary contacts I6 are rigidly and insulatedly attached to one end of the supporting structure I2 and electrically associated with a terminal II. These contacts cooperate with the movable contact I8 as the bimetallie member moves from one operative position to another.

Adjusting means 20 consists, in this instance, of a screw which is threadedly attached to the base I2. within the threaded aperture 32. The screw or adjusting member 20 is also adapted to threadedly engage the furcation of the bimetallic member through aperture 33 in a manner as hereinafter described. The adjusting means 22 comprises a screw member which is, in this instance, threadedly attached to the base I2 within the aperture 21. The adjusting member or screw 22 is positioned beyond the end of bimetallic member I4 and does not engage such member except when it is in an inoperative position as hereinafter described.

The manual reset mechanism 24 comprises a shaft 48 slidably mounted within the aperture 30 in base I2, a resilient member 52, fiat button 50 and a small pin 5I. The pin 5I' is adapted t0 extend through the upper end of the shaft or stem 48 so as to prevent the shaft 48 from being pulled down through the aperture 30 in the base I2. The button 50 isrigidly attached to or integral with the lower end of the shaft 48 while the resilient member 52 is operatively associated with the lower surface of the supporting structure I2 and the upper surface of the button 50. Accordingly, the resilient member 50 biases the shaft 48 downwardly against the pin 5I.

When assembling the thermostatic device embodying my invention, the supporting structure I2 is cut from a suitable stock material and the apertures 21, 28, 30, 35 and 36 are cut or punched therein. The supporting ledge is then integrally attached to the base I2, forming a part thereof, with the apertures 34, 35 and 36 extending therethrough. The bimetallic member I4 with the apertures 39, 4I and 43 located within the ends of the furcations 38 and 40 thereof is then positioned upon the supporting ledge 26, with the apertures 39 and 4I in furcation 38, cooperating with apertures 34 and 35 in the supporting structure I2, and the aperture 43 in furcation 40 cooperating with the aperture 36 in the supporting structure. It therefore follows that, inasmuch as the apertures 35 and 36 located on the supporting structure are in a straight line, and that, inasmuch as the cooperating apertures 4I and 43 in the bimetallic member I4 are oilset.-

the furcation 40 will b compressed or bowed, say, upwardly as illustrated in Fig. 3. It is to be understood that, if desired, the apertures 35 and 36 may be positioned out of line with the cooperating apertures 4I and 43 located in a straight line. This procedure would likewise bow the furcation 40 upwardly, as hereinabove described.

The furcation 40 will thus be in compression. Conversely, the furcation 38 will thus be in tension. The furcated bimetallic member I4 is thus attached to the structure by means of furcations v 38 and 40 with one furcation 40 in compression and one furcation 38 in tension, so as to produce a snap acting action of such member as it changes from one operating position to another.

The adjusting means 20 is then threadedly inserted through the aperture 33 in furcation 40, and through the aperture 32 in the supporting structure I2. Accordingly, the screw or adjusting means 20 -may thus, depending upon the relative rotation thereof, raise or lower the furcation 40 upwardly or downwardly with respect to the base I2. This, in turn, increases or decreases the compression within the furcation 40 and accordingly adjusts the disengaging or opening temper-1 over the bimetallic member I4. Accordingly, the headof the adjusting screw 22 may be moved vertically relative to the supporting structure I2 and limit the upper position of the bimetallic member I4 when in a disengaged position (see Fig. 4). This, in turn. aords adjustable means of varying the inoperative position or closing temperature of the bimetallic member.

The device embodying my invention thus includes, in combination, a supporting structure, a furcated bimetallic member attached to the structure with one furcation thereof in compression and one in tension, with adjustable means cooperating with the compressed furcation for varying the degree of compression of such furcation for adjusting the operation of such member,

and a second adjusting means cooperating withl the free end of the bimetallic member for varying the closing temperature of such thermostatic device. i

The thermostatic structure II) may be operatively associated with the supply circuit 56 (see Figs. 10 and 11) with the furcations 38 and 40 of the bimetallic member I4 being either in series or in parallel with the supply circuit. With the furcations 38 and 40 in series with a resistor, or the like 58, the circuit through the resistor 58 may include the conductor 60, furcation 40, end portion 42, furcation 38, conductor 62, stationary contact I6, movable contact I8, a second stationary contact I6 and a resistor 58 to the supply circuit 56. Accordingly, it follows that when the thermostatic device Ill is in an operative position with the movable contact I8 engaging the stationary contact I6, the full amount of current passing through the resistor 58 willl pass through each furcation of the bimetallic member. Then as the bimetallic member I4 increases in temperature, either due to the passage of current therethrough or to a suitable increase in the ambient temperature thereabouts, or both, the bimetallic member I4 will snap upwardly, disengaging the contacts I6 and I8 (see Fig. 4). The current passing through the resistor 58 to the power supply is thus interrupted.

Then, as the bimetallic member I4 cools to its closing temperature, such member will snap back to its operative position where the contacts I6 and I8 again become engaged. However, if it be desired tov close the bimetaliic member by hand, the button 50 and shaft 48 of the manual resetting device 24 would be pushed upwardly against the compressed or bowed furcation 40 of the bimetallic member I4 causing such furcation to arch upwardly and the movable contact I8 to be moved downwardly with a snap action. The bimetallic member would thus remain closed if the temperature be close to the closing value, and would return to an open position if the temperature is not of such magnitude.

If the resistor should be of a considerably greater capacity such as resistor 59 illustrated in Fig. 11, it may be desired to have the furcations 38 and 40 in parallel. Accordingly, the current passes through the resistor 59 to the stationary contact I6, movable contact I8 and then divides, and equal portions thereof traverse the respective furcations 38 and 46 to the conductor 6I and the supply circuit 56. However, the thermal operation of the thermostat remains substantially as hereinabove described in which the bimetallic member operates with a snap action.

If it be desired, an additional or modified form of adjusting means 6 6 may be used to adjust the degree of compression within the furcation 40 of bimetallic member I4. When using the adjusting device 66, the supporting ledge 26 comprises two members 68 and 10. The portion 68 is rigidly attached to, or integral with, the supporting structure I2 (see Fig. 5). The portion I0 is movably or slidably attached to the supporting structure I2 while the furcation 40 of bimetallic member I4 is rigidly attached thereto. The adjusting means 66 includes a flange portion 12 which is functionally integral With the stationary member 68 and an adjusting screw lI4 threadedly engaged therewith. The adjusting screw i4 is adopted to contact the outer edge of the movable portion 'I0 of the supporting ledge 26. Thus, as the adjusting screw 'I4 is rotated inwardly or outwardiy, the slidable portion 'I0 and the end of the furcationlIU are likewise moved inwardly or outwardly. The compression within furcation is thus either increased or decreased while the shape of the furcation is likewise changed. Accordingly, it follows that the adjusting mechanism @E may likewise selectively adjust the degree of compression within the furcation 40 so as to adjustably vary the operating characteristics of the bimetallic member I4.

If it be desired, the bimetallic member I4 may be permanently deformed so as to increaseV the relative lengths of the furcations of bimetallic member I4 after having been cut a uniform length.

Referring to Figs. 6 and 7, it will be observed that the furcation 38"of bimetallic member I4 has been subjected to a crimping operation in which a series of waves or undulations 'I6 have been formed therein. These waves or undulations have the eiect of decreasing the length of the furcation 38.

Accordingly, it is obvious that when the bimetallic member I4' is attached to the supporting structure I2 in whichthe apertures 35 and 36 of the supporting ledge 26 are in a straight line, as hereinabove described, the furcation 4U will be bowed upwardly and will be subjected to compression, while the corrugated furcation 38 will be under tension.

As an additional modification of the bimetallic member I4, the leg 40", after having been formed, may be substantially reduced in thickness or coined so as to increase its length. The bimetallic member I4" (see Fig. 8) will thus have two or more substantially at furcations 38' and 40" with 40 being substantially longer than the furcation 38". Accordingly, as hereinabove described, when the bimetallic member I4 having furcations of uneven length, is attached to the supporting structure I'2 in which the apertures are substantially in a straight line, the furcation 40 having the longerlength will be under compression, While the shorter furcation 38 will be under tension.

Various other modifications may be made in the device embodying my invention without departing from the spirit and scope thereof, and I desire, therefore, that only such limitations shall be placed thereon as are imposed by the prior art and the appended claims.

I claim as my invention:

1. A thermostatic device including, in combination, a supporting structure and a furcated bimetallic member having aclosed end, said member attached to the structure so that one furcation is attached to said structure at a different effective distance from said' closed vend than the other thereby to cause one furcation to be in compression and one in tension to produce a snap-action of such member.

2. A thermostatic device including, in combination, a supporting structure and a furcated bimetallic member having a closed end, said member attached to the structure by means of the ends of the respective furcations being xed at different effective distances from said closed end so that at least one furcation is in compression and one in tension to produce a snap-action of such member.

3. A thermostatic device including, in comblnation, a supporting structure, a furcated bimetallic member attached to the structure with one furcation in compression and one in tension, and means cooperating with the compressed furcaiion for varying the shape thereof for adjusting the operation of such member.

4. A thermostatic device including, in combination, a supporting structure, a furcated bimetallic member attached to the structure with one furcation in compression and one in tension, and adjustable means cooperating with the compressed furcation for varying the degree of compression of such furcation for adjusting the operation oi such member.

5. A thermostatic device including, in combination, a supporting structure, a furcated bimetallic member attached to the structure with one furcation in compression and one in tension, and adjustable means cooperating with' the cornpressed furcation for adjusting the operation of such member, and adjustable means cooperating with the free end of the bimetallic member for adjusting the operation of such member.

6. A thermostatic device including, in combination, a supporting structure, a furcated bimetallic heat-responsive member, said member attached to the structure by means of the furcations with one furcation in compression and one in tension for producing a snap-action of such member, cooperating contacts, one of such contacts attached to the support and a second attached to the free end of the bimetallic member, an adjusting member cooperating with the structure and the compressed furcation for adjusting the contact disengagement temperature of the bimetallic member, and a second adjusting member cooperating with the structure and the free end of the bimetallic member for adjusting the contact reengagement temperature of the bimetallic member.

'7. A thermostatic device including, in combination, a supporting structure, a furcated bimetallic heat-responsive member, said member attached to the structure by means of the furcations with one furcation in compression and one in tension for producing a snap-action of such member, cooperating contacts, one of such contacts attached to the support and a second attached to the free end of the bimetallic member, an adjusting member cooperating with the structure and the compressed furcation for adjusting the contact disengagement temperature- 

